The present invention relates to colorants for the mass coloring of polymers. In the mass coloring of polar polymers in particular, examples being polyamides, polyesters, polycarbonates and ABS, stringent requirements in terms of their heat stability and light fastness are expected from the dyes used.
The object of the present invention is, therefore, to provide heat-stable, light-fast and readily polymer-soluble colorants.
It has been found that the compounds of the formula (I) defined below achieve the stated object.
The invention, therefore, relates to the use as a polymer-soluble colorant of a compound of the formula (I) 
in which R1, R2, R3, R4, R5, R6, R7, R8, Rxe2x80x25, Rxe2x80x26, Rxe2x80x27, Rxe2x80x28 are hydrogen, halogen, hydroxy, xe2x80x94NO2, xe2x80x94CN, xe2x80x94CF3, xe2x80x94CONH2, C1-12alkyl, phenyl, naphthyl, phenanthryl, anthryl, R9R10Nxe2x80x94, R9xe2x80x94Oxe2x80x94 or R9xe2x80x94Sxe2x80x94, xe2x80x94CONHR10, xe2x80x94CONR9R10 in which R9 and R10 are C1-C6-alkyl, C6-C10-aryl, (C6-C10)-aryl-(C1-C6)-alkyl or (C1-C6)-alkyl-(C6-C10)-aryl, in which the alkyl and/or aryl radicals can be substituted by hydroxyl, C1-C6-alkoxy, C6-C10-aryloxy or halogen; and optionally two adjacent groups can form an isocyclic or heterocyclic group.
Preferred compounds of the formula (I) are those in which each R1, R2, R3, R4 is hydrogen, halogen, methyl or nitro.
Compounds of the formula (I) which are also preferred are those in which R5, R6, R7, R8, Rxe2x80x25, Rxe2x80x26, Rxe2x80x27, Rxe2x80x28 are hydrogen, methyl, chlorine, xe2x80x94CF3 or CONH2.
Preference is also given to compounds of the formula (I) in which two adjacent groups of the series R5-8 and Rxe2x80x25-8 form heterocyclic rings of the following type: 
in which R11, R12 are independently hydrogen, C1-12alkyl, phenyl, naphthyl, phenanthryl.
Particular preference is given to compounds of the formula (I) in which R11, and R12 are methyl, ethyl, phenyl.
Novel compounds according to the invention have the structure of formula (I) in which at least one of the substitutents R1, R2, R3, R4, R5, R6, R7, R8, Rxe2x80x25, Rxe2x80x26, Rxe2x80x27 or Rxe2x80x28 has the meaning xe2x80x94CN, xe2x80x94CF3, xe2x80x94CONH2, phenyl, naphthyl, phenanthryl, anthryl, R9R10Nxe2x80x94, xe2x80x94CONHR10 or xe2x80x94CONR9R10 as defined above, as well as the compounds where two adjacent groups form an isocyclic or heterocyclic group.
The present invention also provides a process for preparing the novel compounds of the formula (I) as defined above, characterized in that a naphtoquinone of the formula (II) 
in which Hal is halogen, preferably Cl or Br, is condensed with compounds of the formula (IIIa) and (IIIb) 
in which Met is hydrogen, Na+, K+ or Zn2+.
Condensation takes place in a molar ratio of (II):(IIIa):(IIIb) of approx. 1:1:1.
Condensation can be conducted without solvent in the melt at temperatures, for instance, of between 150xc2x0 C. and 300xc2x0 C., preferably up to 250xc2x0 C., or in an inert solvent at temperatures between 25xc2x0 C. and 300xc2x0 C., preferably between 100xc2x0 and 250xc2x0 C., in the presence or absence of a catalyst, at atmospheric pressure or under pressure.
Examples of suitable solvents are relatively high-boiling aliphatic or aromatic, substituted or unsubstituted hydrocarbons, examples being xylene (mixture), biphenyl, nitrobenzene, chlorobenzenes, chloronaphthalene, glycol ethers, organic acids and acid amides, especially dimethylformamide, dimethylacetamide or N-methyl-pyrrolidone.
Examples of possible catalysts are inorganic or organic acids, such as hydrochloric or sulphuric acid, benzenesulphonic, toluenesulphonic acid, or acetic acid. The salts of organic acids, such as sodium or potassium acetate, are in many cases also suitable as catalysts.
Whereas the compound of formula (IV) 
is not heat stable in polyester or polyamides, it is surprising that the compound of formula (V) for example is heat stable in polyamide (up to 300xc2x0 C.) and also in polyester up to 320xc2x0 C. The compound of formula (V) has also a very good light fastness in polyester. 
The compounds of the invention are eminently suitable for the coloring of melts of synthetic polar polymers such as, for example, ABS, polyester, polycarbonate or polyamides. Polyamides are, for example, polycondensation products or addition polymerization products of dicarboxylic acids and diamines, e.g. of adipic acid and hexamethylenediamine, of lactams, e.g. xcex5-caprolactam, or of aminocarboxylic acids, e.g. xcfx89-aminoundecanoic acid. The polyamide melt mixed with the pigment is brought into its final form by conventional methodsxe2x80x94for example, in melt spinning, injection molding, extrusion or film blowing machines.
Some of the dyes of formula (I) give a fluorescent coloration in synthetic polar polymers such as, for example, ABS, polyester, polycarbonate or polyamides.
The dyes of the formula (I) are extremely stable to the heat stress which is necessarily part of the coloring of synthetic polyamides, and the substrates mass-colored with them also display excellent fastness properties, especially light fastness. Their high polymer-solubility is particularly noteworthy.
The compounds of the formula (I) are also suitable as colorants in electrophotographic toners and developers, such as one- or two-component powder toners (also called one- or two-component developers), magnetic toners, liquid toners, polymerization toners and specialty toners (literature: L. B. Schein, xe2x80x9cElectrophotography and Development Physicsxe2x80x9d; Springer Series in Electrophysics 14, Springer Verlag, 2nd Edition, 1992).
Typical toner binders are addition polymerization, polyaddition and polycondensation resins, such as styrene, styrene-acrylate, styrene-butadiene, acrylate, polyester and phenol-epoxy resins, polysulphones, polyurethanes, individually or in combination, and also polyethylene and polypropylene, which may comprise further constituents, such as charge control agents, waxes or flow assistants, or may be modified subsequently with these additives.
The compounds of the formula (I) are suitable, furthermore, as colorants in powders and powder coating materials, especially in triboelectrically or electrokinetically sprayable powder coating materials which are used for the surface coating of articles made, for example, from metal, wood, plastic, glass, ceramic, concrete, textile material, paper or rubber (J. F. Hughes, xe2x80x9cElectrostatics Powder Coatingxe2x80x9d Research Studies, John Wiley and Sons, 1984).
Powder coating resins that are typically employed are epoxy resins, carboxyl- and hydroxyl-containing polyester resins, polyurethane resins and acrylic resins, together with customary hardeners. Combinations of resins are also used. For example, epoxy resins are frequently employed in combination with carboxyl- and hydroxyl-containing polyester resins. Typical hardener components (as a function of the resin system) are, for example, acid anhydrides, imidazoles and also dicyanodiamide and its derivatives, blocked isocyanates, bisacylurethanes, phenolic and melamine resins, triglycidyl isocyanurates, oxazolines and dicarboxylic acids.
In addition, the compounds of the formula (I) are suitable as colorants in ink-jet inks, both aqueous and non-aqueous, and in those inks which operate in accordance with the hot-melt process.
In the examples below, parts are by weight.